Pulse-signal translating arrangement



May 20, 1952, J. T. YATEs ET AL PuLsEs1GNAL TRANSLATING ARRANGEMENT Filed Oct. 23, 1948 ATTORNEY form having pulse durations of two values comprises a univibrator having stable and unstable operating conditions and including an input circuit arranged to have the above-mentioned signal applied thereto. The arrangement also comprises a control circuit coupled to the input circuit and proportioned to maintain the univibrator in a stable de-energized operating condition time-constant circuit is so proportioned as to maintain the univibrator in its unstable operating condition for an interval longer than the shorter-duration pulses of the signal but shorter than the longer-duration pulses thereof, whereby the univibrator translates the signal to develed in the intermediate-frequency amplifierl It and applied to the detector I5. The modulation components of the signal are derived by the detector I5 and areapplied tothe video-frequency amplifier I6 wherein they are amplied and from which they are applied, in the usual manner, to a brilliancy-control electrode of the image-reproducing device I'I. Modulation components derived in the detector I5 are also applied to the synchronizing-signal separator 2G which separates thesynchronizing components from the compositetelvision signal and supplies the fieldfrequency and line-.frequency signals to the synchronizing control circuits of the respective fieldscanning generatorIS and line-scanning genery ator I9. VScanning waves are generated by the generators I8 and I9, in synchronism with the synchronizing-voltage pulses applied thereto op the shorter-durationpulses primarily only in one of the output circuits and to develop the longer-duration pulses primarily in the other of the output circuits.

For a better understanding of the present invention, together with vother and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out inthe appended claims.

Referring now to the drawing, Fig. 1 is a circuit diagram, partly schematic, of a complete television receiver embodying the present invention in a particular form; and Fig. 2 represents graphically Voltage relationships occurring at selected points in the Fig. 1 arrangement and is used as an `aid in explaining the operation of the inven- Referring now more particularly to Fig. 1 of the drawing, the receiver shown is of the superheterodyne type' including an antenna system IIJ, II coupled to a radio-frequency amplifier I2 to which is coupled in cascade, in the order named, an oscillator-modulatorv I3, an intermediate-frequency amplifier I4, a detector I5, a video-frequency amplifier IB, and an image-reproducing device I'I. A field-scanning generator I8 and a line-scanning generator I9 are coupled to an output circuit of the detector I5 through a synchronizing-signal,separator 20, more fully described hereinafter. The eld-scanning generator I8 and the line-scanning generator I9 are coupled to field-deecting and line-deflecting windings, not shown, associated with the imagereproducing device I'I in conventional manner. A sound-signal translating channel 26 and associated loudspeaker 2l are coupled to an output circuit of the intermediate-frequency amplifier I4 in order to translate and reproduce sound signals accompanying the received television program. The stages or units Ill- 21, inclusive, with the eX- ception of unitpresently to be described, may all be of conventional -well-known construction so that detailed illustrations and descriptions thereof are deemed unnecessary herein.

Referring briefly to the operation of the system just described, television signals intercepted by the antenna system I0, II are selected and amplified in the radio-frequency .amplifier I2 and are applied to the oscillator-modulator I3 wherein they are converted into intermediate-frequency signals. The latter in turn are selectively amplifrom the synchronizing-signal separator 29, and these generated waves are applied to the scanning elements of the image-reproducing device I'I to deflect the scanning ray of the latter in two directions normal to each other so as to trace a rectilinearscanning pattern on the screen of the device I'I and'thereby reconstruct the transmitted image.

Referring now more particularly 'to that portion of the receiver of Fig. 1 which embodies the present invention, the synchronizing-signal separator20is essentially a pulse-signal translating arrangement comprised by a transitron typeof univibrator which includes a vacuum tube 33 having an anode 3I, a cathode 32, a space-current control electrode 33, and a plurality of electron-permeable intermediate electrodes which may comprise a screen electrode 34 and a suppressor electrode 35. The screen electrode 34 and suppressor electrode 35 are intercoupled vby a time-constant circuit, comprising a vseries-coupling condenserr36 and a shunt 'resistor 3l connected between the suppressorv electrode 35 and ground, which is eiective to return the univibrator to a stable-operating condition a predetermined time interval after an unstable operating condition thereof has been established. The univibrator includes two output circuits in which the voltages thereof vary in opposite senses with changes from'one of the aforementioned operating conditions to the other. In particular, one of these output circuits comprises the anode circuit ofthe tube 30 and is coupled to the synchronizing-input circuit of 'the field-frequency generator I8.' This circuit includesan anode load resistor 38 with shunt-connectedcondenser 39,' the resistor 38 coupling the anode 3I of the tube 3B to a source ofv energizing potential, indicated as -I-B. The other output circuit last mentioned -is coupled to the line-frequency generator I9 and includes a resistor 40 which couples the screen electrode 34 to a source ofv energizing potential, indicated as -l-Sc; The unit 20 includes a' control circuit, to which is applied the composite television signal derived in the output circuit of the detector I5and including'synchronizing-signal components having pulse durations of two values, effective to maintain the univibrator 3'0 in a de-energized operating condition in the intervals between the pulses of the signal but to causel the'univibrator to initiate operation in its unstableope'rating condition v'upon "the occurrence of each pulse ofthe signal. This lcontrol circuit is coupled to the space-current control'electrode' 33 of the tube' 39 and'includes'a series' `resistor 4 I; a shunt resistor 42, and a series-coupling condenser 43.

Consideringnovvthe operation. of. the. pulse-.- signal translating Carrangement just .described-,1. andfreferring` to the curves of Fig.4-2,=thecom.=.. posite television signalw -derived in .the output` cir-..- cuit.. of.. thedetector. I5 is. applied through.. the. y coupling condenser. 43. to the space-current con-,Q trol electrode 33' of the tube 30. The applied'.

signal has such .polarity that the synchronizingsignal-A pulses of the .composite signal.

nal componentsfrom the video-frequency components. The operationis much as 4though .a .sig-

nal .having the Wave-form representedby curve A. of: Fig. .-2 were applied Ato vthe electrode-33 ofthe tube 3B. The synchronizing .signal representedby curve A is shown-as comprising two conven-- tional Vequalizing pulses- P1 and P2 lWhich precede: a serrated field-synchronizing pulse Pronly- .a

portion` of which is shown.

In the intervals- `between the synchronizing j' pulses of the television signal, the anode 3| is at. the full V-|-B -potentialand the screen electrode34 v isat the -full -i-Sc-potential since the tube Y3l) is biased to-space-current cutoff as previously menrtioned. The application to the control electrode.

33 of a synchronizing pulse P1 causes the tube:

The potential of -the anode 3| thereupon tends suddenly to 3i) lsuddenly tobecome conductive.

fall, but the simultaneous fall in the potentialz of theVv screenrelectrode34fis coupled through the condenser 33'- to thesuppressor electrode -35- to eiect an almost intantaneous reduction offthe anode-current to zero Value and thereby `return- This extremely Y, short pulse-spike of anode potential variation 45 is in practice usually negligible even in the ab the anode 'to -full y+B potential.

senceof'the condenser 39g but is entirely -removed by the use-of the condenser 39 which" maintains'essentially' constant the voltage of the'` anode during its vmomentary conductive intervalf The decrease ofpotentialaof the suppressorelectrode -35 accelerates th'e:fincrease of screen-elecftrod-e currentand decrease .of screen-electrode.I potential in a mannerwhich is characteristicof transitron operation. The decreaseof screenelectrode potential lcontinues vuntil a stable condi.-

tion is reached Yatvvhich maximum current-flowsv ini the nscreen-electrodeY circuit. ThereA consequently ismdeveloped across the screen-electrode a resistor i3-for application to the line-frequency.A generator .19,` a potential pulse of negativer polar-t ity'asrindicatedbypulse P1 of curve B; The couplingfcondenser y36 vis..-normal1y charged' to; the fullv value of the screen-electrode-potential-y +Sc during. .the interval. when the tube 30- iscut oth'. andthus begins toldischarge-ithrough.

the resistor .31vvhenthe `screen electrode v311v becomes. conductive. The .potential applieclto the..

suppressor electrode 35 lconsequently rises .exponentially toward zero valuefbut;v the synchronizing pulse P1 `terminatesbefore the suppressor electrode voltage .has .decreased to .a Valuerwhich.

permits the .ow of Vcurrent to the 4anode....3l..

Since -the .tube 30 'is'..again biased to .space-cur.- rent cutoifat the termination of the synchronize.

ingpulseu'therpQtential-fot;the:screen electrode n 3 4 .sagaine returns@toyftheeffull- 2 potentialA of lthe 1 source-@Esci and.the..condenser-3tif-again recharges tothelfuliavaluegef theflattere- The-resulting potenti-alevariatiorreof ..the suppressor Yelectrode -35 is .represented-l byfcurv.e,-.-.C A.ci .Figi y2. It. will benoted-:fromL thegoperatonmthus @far described,

thattheaeieettoff'thefpulse -P1. is -:to develop rat the screens electrode 34..- an -.an1plifiev.'lA and-.Wellden-ned:V pulse, ethe, .-length off-which isfapproximately;` thesame fasL that-iofrthe" applied .pulse P1. This described'roperation.prevails -for'the second equalizing @pulsePz'fandfflikewise:prevail-s `for .reach oie-thedine-synchronizing pulses-fof the television'- signaler.

Upoxx-ith`ez-` appiication-tc the control .n electrode 33foli..theftield-synchronizingv pulse P3A of the televisionefsignalgf.thernitialgoperation issthat previouslyueseribeaeimtnauthe. anode-3| -of the tube 30:f-.momsentarily'` draws current but is almostimmediatelygrenderedsnonconductive-by the suddendrop-off qtentialfotfthei suppressorelectrode 35 consequent.- uponethefcorresponding@droppf potentialaoffsthe estiment-electrode 34.. Nova howtionfthat-.theqcondenser- 6;.' discharges -sufliciently thatuthe-pqtri-tialeof I.the-.fsuppressor .electrode 35 permitsftheflow .current-.to theanode 3 IA.A The moment that this occurs, the flow of anode curarent'zreduces .theieurrent to the-screen electrode 34.- Thisfdecreasesethe.- potential drop-across the i screencircuitxresistonlwithfthe result that the suppressor @electrode-35.- `is fdriven more Trapidlytowar-.d lzero1potentlalathus-furtherto increase theanode current Landtdecrease Y the -screenelectrode...current.. Thies-.factionsiscumulative and causes-.thee-anode; potential-tol decrease almost instantaneously. tota value .as represented V`bycurvefDw. Thelsereen-.el'ectrode-potential simi-- larly.increasessuddenlyrtoa .valuethat is slightly lesstliantthepotential:ofthe` source -l-Sc, as indicated by curve B,-.due.-tol `ther-fact that the screen-electrode. purr-.ent` -isenot` entirely cut 01T. Thepoten-tials..of.A the. anode-.3 l.r and screen electrode-.34-remain at. these fvafluesfuntil 'the' termination.- of-the `gpulse =-.-P3.,..\whereupon the tube y 33 is .againfbiasedmo#space-current cutoff -by -the seltabiastpotential..developed-by the control electrodee33... At ...this stime, -the Afpotential of'v the anode .3 'I'. again .increases to 'the' full .value1 of the source' +B to terminate the first of the amplinedand repeated held-frequencyv synchronizing pulsesdeveloped. acrosgthe anodeI resistor. 38 and applied..l`to.:tlieinem-frequency generator I8. It v.vvilllbe noted lthatreach field-synchronizing pulse P3", de1velo'jpsLinfihefanode circuit .of-the tube 3! a .Well-Lideedjlamplid. fpulse'having a very steep leadiiigSedge,.gtheflength of thev pulse being the. dirence "between the. .length of .the eldasynchonizing. puls'eandthe length ofl the period required.'forlthzunivibrator. togo. through a cvcle of .transition opera-tient'.`

yIt'willllbe. appreciated from theY .above description rofgpthe loperation .that .the time constant of thecondensenli and resistor 31. must .be longer than...th'e duration ...or the. line-frequency synchronizingpuls'esLbut "shorter-.than the duration of '.'tlielneld-requency synchronizing pulses.

Th`ereis`...th'ev important. advantage with the f translatiiigarrangement.describedthat any feedbacklni fliii'efrequency pulses .i generated by the generator fl 3 "d 4.noi-,flancot fthe. .desiredsynchroniz'ed operationfLofl-Llathe; generator l 8 since the anodef currentyov the.. -tube 'has yzero value. for

the .L 'durationlfoij each. .line-synchronizing pulse 7 Similarly, any feedback of pulses generated by the field-frequency generator I8 will affect the wave form of the potential developed in the circuit of the screen electrode 34 only in the event that the anode potential falls below the knee of the anode-voltage-current characteristic to cause the anode current to decrease, a condition which is not likely to occur in practice since the value of impedance of the anode load resistor 38 is relatively low. If such should occur, rhowever, the only result will be to increase the screen current and thus reduce the potential of the screen electrode 34 during the interval between the end of the period of transitron operation and the end of the field-synchronizing pulse, but this does not in any manner affect the desired synchronized operation of the line-frequency generator I9. Minimized feedback of energy from one of the generators I8 and I9 to the other is thus attained by utilizing` a relatively low value of resistance for the anode resistor 38 and a relatively large value of resistance for the screen-electrode resistor 40 so as to enhance the transitron mode of operation. If desired, the screen-electrode resistor 40 may be replaced by a pulse transformer to provide ahig'h-impedance load in the screen-electrode 'circuit with a lowimpedance output winding coupled to the generator i9. Y

It will be apparent from the above description of the invention that a pulse-signal translating arrangement embodying the invention has high utility as a synchronizing-signal separator of a television receiver and that, when it is so used,

it eiects by the use of a single tube the separation of the line-synchronizing and field-synchronizing pulses not only from the video-frequency components of the television signal but also from each other. The present arrangement has the additional advantage that it is of simple and inexpensive construction and is characterized by high reliability of operation.

While there has been described what is at present considered to be the preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modications may be made therein without departing from the invention, and it is, therefore, aimed to cover all such changes and modifications as fall Within the true spirit and scope of the invention.

What is claimed is:

l. A pulse-signal translating arrangement for translating a signal of pulsewave form having pulse durations of two values comprising: a univibrator having stable and unstable operating conditions and including an input circuit arranged to have said signal applied thereto; and a control circuit coupled to said input circuit and proportioned to maintain said univibrator in a stable de-energized operating condition in the intervals between the pulses of said signal but to cause said univibrator to initiate operation in said unstable operating condition upon the occurrence of each pulse of said signal; said univibrator including two output circuits in which the voltages thereof vary in opposite senses with changes from one of said operating conditions to the other, one of said output circuits including a time-constant' circuit so proportioned zand arranged as to maintain said univibrator in said unstable operating condition for an linterval longer than the shorter-duration pulses of said signal but shorter than the longer-duration pulses thereof before permitting said univibrator to return to said stableoperating condition, whereby said univibrator translates a signal representative of said signal to develop said shorter-duration pulses primarily only in one o f said output circuits and to develop said longerduration pulses primarily in the other of said output circuits.

2. A pulse-signal translating arrangement for translating a signal of pulse wave form having pulse durations of two values comprising: a univibrator having stable and unstable operating conditions and including at least one vacuum tube having a space-current control electrode arrangedto have said signal applied thereto; and a control circuit coupled to saidcontrol electrode .and proportioned to develop a unidirectional bias effective to maintain said univibrator in a stable de-energized operating condition in the intervals between the pulses of said signal but to cause said univibrator to initiate operation in said unstable operating condition upon the occurrence of each pulse of said signal; said univibrator including two output circuits in which the voltages thereof vary in opposite senses with changes from one of said operating conditions to the other, one of said output circuits including a timefcolnstant circuit so proportioned and arranged as to maintain said univibrator in said unstable operating condition for an interval longer than the shorter-duration pulses of said signal but shorter than the longer-duration pulses thereof before permitting said univibrator to return to said stable operating condition, whereby said univibrator translates a signal representative of said signal to develop said shorrduration pulses primarily only in one of said output circuits and to develop said longer-duration pulses primarily in the other of said output circuits.

3. A pulse-signal translating arrangement for translating a signal of pulse Wave form having pulse durations of two values comprising: a univibrator having stable and unstable operating conditions and including an input circuit arranged to have said signal applied thereto; and aA control circuit coupled to said input circuit and including means for maintaining said univibrator in a stable de-energized operating condition in the intervals between the pulses of said signal but to cause said univibrator to initiate operation in said unstable operating condition upon the occurrence of each pulse of said signal; said univibrator including two output circuits in which the voltages thereof vary in opposite senses with changes from one of said operating conditions to the other, one of said output circuits including a time-constant circuit so proportioned and arranged as to maintain said univibrator in said unstable operating condition for an interval longer than the shorter-duration pulses of said signal but shorter than the longer-duration pulses thereof before permitting said univibrator to return to said stable operating condition, whereby said univibrator translates a signal representative of said signal to develop said shorterduration pulses primarily only in one of said outputcircuits and to develop said longer-duration puroses primarily in the other of said output circui s.

A' 4. A pulse-signal translating arrangement for translating a signal of pulse Wave form having pulse durations of two values comprising: a univibrator having stable and unstable operating conditions and including an input circuit arranged to have said signal applied thereto; and

failing-sas a control circuit coupled to saidinputcircuit and including a source of fbias potential relieving; a

- value Aso related to the amplitude of 'said-signal f as tomaintainsaid. 4univibrator-f in al sta'fblesde-` energized operating ,.conditiornin the intervalsY between the pulses of 'said'signal but to cause said univibrator to initiate-.operation in-:saidaun- Vstable. operating.. condition., upon the #occurrence of each1pulseofsaid.signale-@said univibrator including two output circuits in which the voltages thereof vary in opposite senses with changes from one of said operating conditions to the other, one of said output circuits including a time-constant circuit so proportioned and arranged as to maintain said univibrator in said unstable operating condition for an interval longer than the lshorterduration pulses of said signal but shorter than the longer-duration pulses thereof before permitting said univibrator to return to said stable operating condition, whereby said univibrator translates a signal representative of said signal to develop said shorter-duration pulses primarily only in one of said output circuits and to develop said longer-duration pulses primarily in the other of said output circuits.

5. A pulse-signal translating arrangement for translating a signal of pulse wave form having pulse durations of two values comprising: a transitron type o-f univibrator having stable and unstable operating conditions, including a vacuum tube having an anode, cathode, and a. plurality of electron-permeable intermediate electrodes and including an input circuit arranged to have said signal applied thereto; and a control circuit coupled to said input circuit and proportioned to maintain said univibrator in a stable de-energized operating condition in the intervals between the pulses of said signal but to cause said univibrator to initiate operation in said unstable operating condition upon the occurrence of each pulse of said signal; said anode and one of said intermediate electrodes being included in individual signal-output circuits in which the voltages thereof vary in opposite senses with changes from one of said operating conditions to the other, said output circuit including the last-mentioned said intermediate electrode also including a time-constant circuit so proportioned and arranged as to maintain said univibrator in said unstable operating condition for an interval longer than the shorter-duration pulses of said signal but shorter than the longerduration pulses thereof before permitting said univibrator to return to said stable operating condition, whereby said univibrator translates a signal representative of said signal to develop said shorter-duration pulses primarily only in one of said output circuits and to develop said longer-duration pulses primarily in the other of said output circuits.

6. A pulse-signal translating arrangement for translating a signal of pulse Wave form having pulse durations of two values comprising: a transitron type of univibrator having stable and unstable operating conditions, including vacuum tube having an anode, cathode, screen electrode and suppressor electrode and including an input circuit arranged to have said signal applied thereto; and a control circuit coupled to said input circuit and proportioned to maintain said univibrator in a stable de-energized operating condition in the intervals between the pulses of said signal but to cause said univibrator to initiate operation in said unstable operating condition upon the occurrence of each pulse of said signal; sadanodeandsad screen electrodefbeing d 'ndvidualgsignal-.output circuitsrn e ci r v :zwhieli'thervoltages. thereof vary in opposite senses with. changes' front Vone ofrsaid .operating`- lconditions 'to' the..;o.t her, said output circuit, including said screen electrode also including a timeconstant circuit -.so proportioned and arranged as to lmaintainssaid.'univibratorin. said unstable operating condition for an interval longer than the shorter-duration-pulses ofisaid signal but shorter .-than thelonger-duration ypulses thereof; before permitting said univibrator-to return tof-said stable operating condition, whereby said univibrator translates a signal representative of said signal to develop said shorter-duration pulses primarily only in said screen-electrode output circuit and to develop said longer-duration pulses primarily in said anode output circuit.

7. A pulse-signal translating arrangement for translating a signal of pulse wave form having pulse durations of two values comprising: a transition type of univibrator having stable and unstable operating conditions and including a vacuum tube having an anode, cathode, space-current control electrode, screen electrode and suppressor electrode; and a control circuit arranged to have said signal applied thereto, coupled to said control electrode and proportioned to maintain said univibrator in a stable de-energized operating condition in the intervals between the pulses of said signal but to cause said univibrator to initiate operation in said unstable operating condition upon the occurrence of each pulse of said signal; said anode and said screen electrode being included in individual signal-output circuits in which the voltages thereof vary in opposite senses with changes from one of said operating conditions to the other, said output circuit including said screen electrode also including a timeconstant circuit so proportioned and arranged as to maintain saidpunivibrator in said unstable operating condition for an interval longer than the shorter-duration pulses of said signal but shorter than the longer-duration pulse thereof before permitting said univibrator to return to said stable operating condition, whereby said univibrator thanslates a signal representative of said signal to develop said short-duration pulses promarily only in said screen-electrode output circuit and to develop said long-duration pulses promarily in said anode output circuit.

8. A pulse-signal translating arrangement comprising: a transitron univibrator having an input circuit, a screen-grid output circuit including a iirst load impedance, a time-constant network coupled to said first load impedance and an anode output circuit including a second load impedance, said univibrator also including a vacuum tube having a control electrode and cathode coupled to said input circuit, said input circuit being arranged to have applied thereto a signal of pulse wave form having pulse durations of two values and said input circuit including means for biasing said control electrode to effect anode-current cutoff of said tube during the interval between said pulses; said tube also having a screen-grid electrode coupled to said screen-grid output, circuit, a suppressor grid coupled through said time-constant network to said last-mentioned output circuit and to said cathode, and an anode coupled to said anode output circuit; the said network being so proportioned that they charging and discharging time constants thereof permit univibrator operation only on the longerduration pulses of said signal, whereby the trans- .said Yunivibrator causes the. shorter-duration pulses of said signal to be developed primarily only in said screen-grid output circuit and causes said longer-duration pulses to be developed pri- 5 marily in said anode output circuit.

JOHN THOMAS YATES. IAN NORMAN VAUGHAN-JONES.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number 12 UNITED STATESv PATENTS i*Name Date Kemp Oct.*31, 1939 Barco Aug. 18, 1942 FOREIGN PATENTS Y Country Date Y Italy Dec. 19,' 1938 Great Britain Dec. 19, 1938 

